At present, distillation column trays as described above and as used in metallurgy for distilling metals are generally rectangular in shape, with the rim surrounding the bottom of a tray then having four plane outside flanks. In addition, the through holes are usually provided in laterally offset portions of the tray bottoms. Thus, the trays are stacked one above another in a distillation column in such a manner as to place said through holes in a zigzag configuration so that the non-pierced portions of the bottoms act as baffles which increase heat exchange between the vapor flowing upwards and the liquid flowing downwards. This type of distillation column is also known as a "New Jersey retort".
When metals having a high boiling temperature are to be distilled, e.g. 907.degree. C. for zinc, the heating chamber for vaporizing the metal, or more precisely the mixture in which the metal to be distilled is engaged, must provide an enormous quantity of heat which tends to increase the cost price of the metal distilled in this way. Attempts have therefore been made to increase the production to energy cost ratio of such distillation columns.
Initially, the trend was to improve the production capacity of distillation units for given energy consumption. To this end, use has been made of columns of larger-sized trays associated with heating chambers attached thereto. However this solution suffers from the drawback of reducing the volume of the heating chambers. In addition, following the sudden increase in the price of oil products, the major concern in the industry has been to reduce the quantity of fuel consumed, while simultaneously making efforts to improve energy efficiencies.
Thus, the technical problem to be solved by the present invention is to provide a distillation column tray of the type specified above that enables the same quantity of distilled metal to be produced for a considerable reduction in energy consumption.